In a substrate processing apparatus for performing a process on a substrate such as a semiconductor wafer, a liquid crystal substrate or a solar cell substrate, particles (foreign substances) on a substrate on which a transfer process or a certain process has been performed are measured. Based on a measurement result, performance of the apparatus is evaluated.
The particle measurement result includes the number or the size (diameter) of the particles, or a particle distribution on the substrate. These measurement results are analyzed together with information (a shape of the apparatus, a gas to be used, a transfer path, a transfer method or the like) of the apparatus, and the analyzed measurement results are used to check the kind or a cause of an abnormality of the apparatus or the process.
Among the particle measurement results, the particle distribution is random in a normal state. If there is an abnormality in the apparatus or the process, the particle distribution on the substrate may have non-uniformity. Accordingly, by determining the abnormality of the particle distribution, it is possible to detect the abnormality of the apparatus or the process.
Japanese Patent Laid-open Publication No. 2009-098123 Japanese Patent Laid-open Publication No. H10-326812 Japanese Patent Laid-open Publication No. 2009-068946 Japanese Patent Laid-open Publication No. 2008-78392
However, the particle distribution is not easy to analyze in comparison with the other measurement results (size, number, etc.). Further, it is very difficult to analyze particle distribution characteristics. Thus, it has been difficult to determine the abnormality of the particle distribution. Accordingly, in order to analyze the particle distribution or detect the abnormality thereof, it is required for an analyzer to have high level of knowledge and experience on the apparatus or the process. Further, there is a difference in determination results depending on analyzers.
Thus, conventionally, the analysis has been focused only on the number, size or composition of the particles (for example, see Patent Documents 1 and 2) among the particle measurement results. Further, until now, an analysis method for detecting the abnormality of the particle distribution has not been established.
Further, there have been conventionally developed analysis methods for a defect distribution, not a particle distribution, on a substrate (for example, see Patent Documents 3 and 4). However, besides the target substrate to be analyzed, these conventional analysis methods also require particle measurement results of other substrates (e.g., normal substrate, etc) for comparison or classification. For example, the abnormality of the particle distribution on the substrate cannot be determined by using a measurement result for only one target substrate.